Mixture control for internal combustion engines



Jan. 26, 1943.

G. R. SISSON MIXTURE CONTROL FOR INTERNAL COMBUSTION-ENGINES Filed Oct.9, 1931 W M N... m m o s W 5 P N 6 n ,z mm 1 y 2 A s: 1J ZMWWHHIIIIIIHHUH n f L Patented Jan. 26, 1943 .nef

MIXTURE ooN'rnoL Fon INTERNAL coMBUsTroN ENGINES Glen R. Sisson,Pendleton, Ind.

Application October 9, 1931,/ Serial No. 567,817

7 Claims. (Cl. 123-119) My invention is concerned with internalcombustion engines of the type to which an explosive mixture is suppliedby means of a carburetor or other, charge-forming device.

It is the object of my invention to provide a control mechanism for thecarburetor or chargeforming device which control mechanism will serve,while the engine is being cranked, automatically to increase therichness of the explosive mixture to an extent depending upontemperature, and which will also serve to control the richness of themixture in accordancewith temperature after the engine is started.

In carrying out my invention I provide in association with thecarburetor a. mixture-enriching 'device such, for example, as the usualchokevalve, and I control this device jointly by a means responsive totemperature and a means which undergoes a change of position .orcondition when the engine becomes self-operative after having been atrest. These various elements are associated in such a way that therichness of' the mixture formed in the carburetor is decreased when theengine becomes self-operative and is decreased further when theengine-temperature rises.

The accompanying drawing illustrates my invention: Fig; 1 is anelevation of the intake and exhaust manifolds and the carburetor of anengine showing my mixture-controlling device in position; Fig. 2 isanenlarged fragmental view similar to Fig. 1; Fig. 3 is a Verticalsection on the line 3-3 of Fig. 1; Fig. 4 is a'view generally similar toFig. l, but showing a modification of my invention; and Fig. 5 is a sideelevation of an automobile engine showing a still further modification.

My invention is not concerned with any particular type of engine. In thedrawing I have illustrated in detail, therefore, only certain parts ofthe engine such as the inlet manifold I0, the exhaust manifold II, and acarburetor I2- The carburetor embodies the usual throttle valve I3 andthe customary choke-valve I4, the latter being located in the carburetorair-inlet I5. In embodying my invention/in association with the variousengine-elements just referred to, the automatic control may be exertedon the choke. valve I4 which, as is well known, serves to in-1.v creasethe richness of the mixture as it is moved toward closed position.

Various parts of the control mechanism are conveniently enclosed in acasing 20 which is preferably mounted adjacent the exhaust manifold I Iof the engine. Within the casing I mount a transversely extending shaft2| to which is anchored the inner end of a spirally wound bimetallicstrip 22, the outer end of which bears upon an abutment provided at theupper end of a link 23. The lower end of the link 23 is connected to anarm 24 that is rotatable with the choke valve I4. .v

The bi-metallic strip 22 is but one example of a temperature-responsiveelement which may be used in carrying out my invention. In the ,n ar-*rangement illustrated in the drawing, the strip is arranged with themetal of higher expansioncoeiiicient toward the outside in order thatthe free end of the strip 22 may rise and permit upward movement of thelink 23 to open the choke valve I4 upon an increase in the temperatureto which the bi-metallic strip 22 is sub- Jected.

. Fixed to the shaft 2| I provide a downwardly extending arm 26operatively connected to a piston rod 21 which carries a piston 28disposed in an associated cylinder 29. A yielding means, such as aspring 3|, acts upon the piston 28 or piston rod 21 tending to move itto the left in Fig. 1, thus tending to depress the free end of thebirmetallic strip 22 to lower the link 23 and move the choke-valve I4toward closed position. The right-hand ,end of the cylinder 29 isconnected through a suitable conduit 32 with the intake manifold I0 ofthe engine in order that the piston 28 may be subjected to the pressureexisting in the intake conduit of the engine above the throttle valveI3. The' left-hand end of the cylinder 29 is in communication with theatmosphere.

' Some means, a particular form of which will hereinafter be described,is provided for maintaining theupper end of the link 23 in contact withthe free end of the bi-metallic strip 22 in order that the choke valveI4 will be moved toward open position as the temperature increases andthe free end of the bi-metallic strip 22 moves upward.

When the engine is at rest, and therefore com-v paratively cold, theparts of my device occupy the respective positions illustrated in Fig.l-andin full lines in Fig. 2. That is, the choke-Valve I4 is closed, andthe piston 28 is displacedfrom the right-hand end of the cylinder 29.If, under these conditions, the engine is cranked for the purpose ofstarting it, an enriched mixture will pass through the intake manifoldII] to the engine. The ow of this mixture will be accompanied by aslight drop in pressure within the manifold I0; but since the crankingspeed of the engine is slow, this pressure-drop will be low and will beinsuilicient to move the piston 28 to the right in opposition to theforce exerted upon it by the spring 3|. When, however, the enginebecomes self-operative, the rate of mixture-flow through the manifold I8increases, and the pressure within the manifold drops to -a valuesuiiicient tov cause the piston 28 to move to 'the right. The resultingmovement of the piston rod 21 rocks the shaft 2| in a counter- 10clockwise direction, elevates the free end of the bi-metallic strip 22,and causes a partial opening of the choke-valve I4, as indicated indotted lines inFig. 2, thus decreasing the richness of the mixturesupplied to the engine by the car- '15 buretor |2:` As the enginecontinues to run, its j temperature., increases, thus causing a furtherelevation of the free-end of the bi-metallic strip 22 and a furtheropening of the choke-valve il. The parts are arranged in such a mannerthat when the engine reaches normal operating temperature thechoke-valve Il will be substantially completely open. Manufacturers ofcarburetors frequently em- 3 ploy a choke valve which is unbalanced,beinj,v

to mov 4so arranged that air-flow past it tends it toward open position.This tendency is, of y course, especially pronounced when the chokevalveis closed, and may be so pronounced as to cause partial opening of thechoke-valve when it would otherwise be held closed by the bimetallicstrip 22. To prevent any such action, I may employl means for lockingthe choke-valve in closed position until after the engine has becomeself-operative. In Figs. 1 and 2, such a locking means in the form o f atoggle is illustrated. The toggle lock just referred to comprises twolinks and 38 which are pivotally interconnected at 31. The upper end ofthe upper link 35 is pivoted at a fixed point in the casing 20; whilethe lower end of the lower link 36 is pivotally connected to thechoke-valve adjusting link 23. Acting between the toggle links I providea spring 38 which tends to raise the choke-,valve adjusting link 23. Thepoints of attachment of the spring 38 to the links 35 and 38 are oiI-setto the right of the centerlines of the respective links in order thatthe spring 38 will tend to move the center toggle-pivot 31 to the leftwhen the three pivot points of the toggle are in line, which conditionexists when the choke-valve |4 is completely closed. One of thetoggle-links, here shown as the link 3i, is provided with an abutment llwhich engages-the other toggle-link to limit leftward movement of themiddle toggle-pivot I1.

. With the construction as described, the chokevalve I4 will be held inclosed position until the toggle comprised by the two links 3B and 33 isbroken; for the choke-valve adjusting link 23 cannot move upward and thechoke-valve cannot open as long as the middle toggle-pivot 31 lies tothe left of the line through the end togglepivots.

By disposing the abutment 48 in line with the end of the piston rod 21,the toggle may `be broken by rightward movement of the piston rod 21which occurs when the engine becomes selfoperative. To permit thebreaking of the toggle without disturbing the shaft 2|, the connection70 between the arm 26 and the piston rod 21 may have a degree oflost-motion suicient to permit the piston rod 21 to move to the rightfar enough to break the toggle without rocking the shaft 2|.

Except when the toggle is locked, as illustrated in full lines in Fig.2, the spring 38 tends to hold the link 23 in contact with the free endof the bimetallic strip 22, as is clear from the dotted-line positionshown in Fig. 2.

Instead of subjecting the piston 28 to the pressure existing within theintake manifold I0, it may be subjected to some other pressure whichundergoes a material change when the engine becomes self-operative.This, in Fig. 5, I have illustrated an arrangement in which the lefthandend of the cylinder 29 is closed and connected to an oil-lineof theoiling system of the engine. Atthe low speed of cranking, the pressurewithin the oil-circulating system of the engine will be insuficient todisplace the piston againstthe action of the spring 3|; but when theengine becomes self-operative, the pressure exerted by the oil on thepiston 28 is increased to such an extent that the piston is moved to theright in the same manner as that in which it is move'd in thevconstruction illustrated in From tl'ie construction described, it willbe apparent that the position of the choke-valve, and therefore therichness of the mixture produced in the carburetor |2, will be dependentupon whether or not the engine is running under its own power and alsoupon engine temperature. As previously described, the device provides atemporarily enriched mixture during the starting operation and abruptlydecreases the richness of the mixture when the engine becomesself-operative, and then gradually decreases the richness of the mixtureas the engine-temperature increases until a normal mixture is producedwhen the engine reaches normal operating temperature. Should the' enginebe stopped after having reached normal temperature, differentiaipressure on the piston 28 will be relieved and the spring 3| will movethe piston to the left to depress the free end of the bi-metallic strip22 and move the choke-valve toward closed position. The extent of thechoking thus produced will depend upon engine temperature, being greaterwhen the engine is cold than when the engine is hot. 'I'his is adistinct advantage of my device for it provides a partial and desirablechoking action during starting of the engine even when the engine ishot.

If desired, the strength of the spring 3| may be made such as to exert acontrol on the chokevalve I4 While the engine is running, in accordancewith varying conditions. Thus, it is well known that a cold engine willoperate with a predetermined degreyof choking at low speeds -but that itwill fail to` operate `satisfactorily as the result of too lean amixture if the throttle is suddenly opened to increase engine-speed.Variations of the pressure "-within -the intake manifold are such as toenable me, by properly proportioning the spring 3|, to provide anincreased choking action if the throttle is suddenly opened when theengine is cold. That is, the pressure-drop within the intake manifold ofthe engine varies from around one inch of mercury during cranking 'withclosed throttle or choke valve to about sixteen inches of mercury whenthe engine is self operative at low speeds and closed throttle. With thethrottle I3 completely or nearly completely open, the pressure-drop inthe manifold I0 will ordinarily not be less than ve inches of mercuryeven at low engine speeds and Will gradually increase as the enginespeed increases.

If lthe spring 3| is so proportioned that it will hold! the'pistomztotheileftwarderidcf its move-w ment against apressure drop 'ofi- .oneinch-ofY mer cu`ry:in:rthevintake-' manir`old,=K completely `col lapse.iandzpermit ektrerne right-ward movement -of s c. the. pistonvwhenithefpressure-drop within the' is connected through the ignitionysvviiichfltt one. l terminalofthe-:battery EGraZnd-thetotheraterminalof thebatterysisgrounded@c, at l 5 In"1iig.'4\ thelpartsrofithtpdevi'cejust-described.V

other endof the fw'inding oflthe. electromagnetSZ-.t

manifoid r1.0 l'is fi'nffthei :neighborhood =o sixteen finchs totmercury', andwillv undergo 'only av 'parL tialllcollaipsetwhenfthepressure :drop Within the' manifdld'fs'm'fthe:neighborhoodrof -iive inches '-off v the-leftward limit 'of its'movement ithus producing its hiaxni'mii l effctf 'in enrichening -thefImixture.

power,l l the' piston l128' Vxfwillf' mov'e fto" f the' extremerightward Ilimitffits? movement and will' produce` the minimum effectit-is`capable ofexercisinglfl the engine-speed increases in responsev,tog-the .'i-

opened throttle, the pressure-drop will increase IIL-Fia ai; hereniging@en ,embodiment of imy lrivehtion in association with'an automaticmixture-control? device' fs'uch las is *set forth'and l? describ`ed inmy co-pending applicationerial No. 532,376, iiled April 23, 1930, nowPatent No.

2,127,653. In that devig-thetchoke-valveIll is?" controlled by changesin the position of a movable member 50 which in turn is controlled by atemperature-responsive element 5| responsive to engine temperature y andmy.. an .electro-magnet 52. In my co-pending 'application `just referredto, the

the electric motor of the engine-starting device so that it is energizedto draw the member 50 downward and move the choke valve il toward closedposition Whenever the engine-starting device is operative. The extent towhich the chokevalve i4 is closed by energizatiorl of the magnet 52 andthe extent to which it is opened after the magnet 52 is de-energizeddepend upon the position of the temperature-responsive element 5I which,through a movable member 53, adjusts stops 54 and 55 that limit closingand opening movements of the -choke-valve I4 respectively.

In associating the invention of this application with the device justdescribed, the magnet 52, instead of being arranged to be controlled bythe starter-switch is connected to a battery' 56 through the switch 51that is usually employed to connect the battery to the engine ignitionsystem, one part of which is indicated at 58. In series with the magnet52,.I place a pressureresponsive switch which is controlled by pressuresin the intake manifold I0 of the engine. This smch may take differentforms, the switch shown comprising a chamber B0 one side of .which isdefined by a movable diaphragm 6I. The chamber 60 is in communicationwith the intake manifold H) of the engine through a suitable tube 62.The diaphragm 6l carries a contact 63 which is grounded and which isarranged to engage a stationary contact 64 that is connected to one endof the winding of the electromagnet 52. The

Cil'

are shownti'ntherpositionstheysoccupy when' the engine isicoxnparativ'elyfcoldfantiy is'f'riot--ini operthe stop s4.Tilefpartsff'taib'r'ess fear stonata' switch are so aftirisertautae'iir'ss'fwmam the intake manifold during the cranking oper- 20 ation isinsuicient to move the contact 63 out of engagement with the contact 64;and as a. result. the choke-valve, during the cranking operation.

remains in the position it assumed when the magn et 52 was energized. Assoon, however-,as the 25" engii'ebegin's .to run. under its own power,pressure within the intakgmanifold-(LB dropsztand thegntact 63 is movedout of engagement with fthifstationary contact 64, thus interrupting thesupply oi' current to the magnet 52 andvpermltting "theichoke-yal'vemove-toward open fposition to .se attent .determined Pri-the, @sitios 0f-zthefswv 55. As the enginecontinues vrun and its tempeiatur increasesl,tlie'lstop 5511s' riovei'l upwardly under thelcontrolfof`thetemperature-responsive element 5|', until the choline-valve M reachessubstanti'ally-'wide-fpen 'position when the n"engine reachesnormali*operating,ftemperature-V I claim as my invention:

l. In combination with an internal combustion engine having acarburetor, an adjustable mixture-enriching device for said carburetor,a movable member, temperature-responsive means acting between saidmovable member andsaid device and nonresiliently connected to thelatter,

45 and means associated with the engine for moving said member in onedirection when the engine is running and in the other direction when theengine stops.

2. A control mechanism for an inter-ral combustion engine carbureterhaving a choke valve comprising, means for locking the valve closed tostart the engine, means actuated by oil pressure in the engine -forunlocking the valve, and a. thermostat for controlling the opening ofthe valve as a function of temperature.

3. A control mechanism for an internal combustion engine carbureterhaving an unbalanced choke valve comprising, a lever connected to saidvalve, latch means engaging said lever to hold the valve closed forstarting, oil pressure actuated means for moving said latch means torelease the valve when the engine res, a thermostat tensioned to holdthe valve closed, and means for decreasing the tensionof the thermostatwhen the engine res to permit the valve to open under the control of thcthermostat.

4. In an internal combustion engine having an intake manifc.d, acarbureter attached to said manifold, a pump driven by said engine, adevice for controlling the richness of the fuel mixture supplied to saidengine by said carbureter, a h'eat responsive device for controlling theoperation of said mixture controlling device, and means responsive topressure derived from said pump for further controlling the operation ofsaid mixture control device.

5. The invention set forth in claim l with the addition that saidtemperature-responsive means and movable member are located remote fromsaid mixture-enriching device, a rigid link connected to saidmixture-enriching device for operating it and extending into associationwith said temperature-responsive means. said temperature-responsivemeans serving to operatively interconnect said movable member and saidlink.

' 6. The invention set forth in claim 1 with the addition that saidmixture-enrichingr device is an unbalanced choke valve located in theairadmission passage or the carburetor and tending to swing toward openposition under the inuence of the air impinging upon it.

7. In combination with an internal combustion engine having acarburetor, an adjustable mixture-em'iching device for said carburetor,a movable member, temperature-responsive means acting between saidmovable member and said device and non-resiliently connected to thelatter, said movable member being movable between two positions in thefirst of which it adjusts said mixture-enriching device to causeproduction of a relatively rich mixture and in the second of which itadjusts said mixture-enriching device to cause production of arelatively lean mixture, and means associated with said engine forcontrolling theposition of said movable member and acting to maintainsaid movable member in said first position when the engine is beingcranked and in said second positon when the engine is running under itsown power.

^ GLEN R. SISSON.

. QERTIFIcAfL'E` oF CORRECTION. j pat-.ent No. 2,5o9,19. f Jamiwyze,191g.

GLEN n. sIssoN.

It is hereby certified that error appears in the printed specificationof the abo ve numbered patent requiring correction es follows: Page Il,first column, lines 5 and 12, for "claim l" residv claim 7"; and thatthe said Letters Patent should be read with. this correction thereinthat the same may conform to the record of the case in the PatentOffice.

signed and sealed 1111s 25rd may -cr'Nuvember,- A; 1yr-19M.4

Henry' Van Arsdale,

(Seal) Acting Commissioner of Patents.

